Charge forming device



Aug. 18, 1931. w. H. TEETER 'GIPARGE FORMING DEVICE Filed Sept. 22. 19274 Sheets-Sheet l NNN,

Aug. 18, 1931. f w. H. -rr-:ETER

CHARGE FORMING DEVICE 4 Sheets-Sheet 2 Filed sept. 22, 1927 ug. 18,1931. w. H. TEETER CHARGE FORMINYDEVICE 4 sheetsl-sheet 3 Filed Sept.-22, 1927 ug. 18, 1931. w. H. TEETER CHARGE FORMING DEVICE 4*Sheets-Sheet 4;l

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-Patented Aug. 18,v 19-31` UNITED STATES PATENT OFFICE WILFORD CFI.TEETER, OF DAYTON, O HIO, ASSIGNOR, BY MESNE ASSIGNMNTS', T0 DELCOPRODUCTS CORPORATION, OF DAYTON, OHIO, A CORPORATION OF DELAW'ARE ACHARGE FORMING DEVICE i Application filed September 22, 1927. Serial No.221,372.

This invention relates to charge forming devices for multi-.cylinderinternal combustion engines and more particularly to the type of chargeforming device or carburetor comprising a plurality of primary fuelmixing chambers or primary carburetors one for each intake port of theengine and cooperatling respectively with a plurality of secondary fuelmixing chambers each located adjacent an .engine intake port andreceiving fuel air mixture from a pipe connected With one of the primarycarburetors and receiving air when required through one branch of an airmanifold which supplies air to all of the secondary carburetors. Theprimary carburetors receive their liquid fuel from a common fuel bowl inwhich the level is controlled by a float valve.

One example of a carburetor to which the present invention relates isthat disclosed in the copending application of Aseltine, Serial No.83,979, filed Jan. 26, 1926. In

the Aseltine carburetor the admission of air wto the air manifold iscontrolled by a spring loaded valve. The throttling of the carburetor iseffected by separate throttle valves one in each secondary carburetorlocated between the secondary mixing chamber and the en gine intakeport. The several throttle valves are controlled by a common operatingmemi ber. The formation of a super-rich fuel mixture in each primarycarburetor and the flow of this mixture to each secondary carburetor iseffected or induced by the flow of A air through the secondarycarburetor and is therefore controlled by the throttle-valve therein.

The general object of this type of charge forming device is to secure amixture of fuel and air in which the fuel is evenly distributed and todeliver equal quantities of said mixture having the same mixture ratioto each cylinder of the engine under various conditions of loadand'speed to which the engine may be subjected, without requiring theheating of the fuel or fuel mixture before it is delivered to theengine. l

When a separate throttle is employed in each of the secondarycarburetors as in the above copending application difficulty maysometimes arise in securing equal distribution of the fuel mixture tolthe several engine ports, because of the diiculty in making the severalthrottles of exactly the same size or securing exactly the sameadjustment of said throttles under all conditions of operation,particularly if said throttles become Worn or warped. v

It is the primary purpose of this invention, to eliminate thepossibility of such difficulty and to secure under all conditions ofoperation equal mixture distribution to the several engine' ports,irrespective of Wear, adjustment or warping of the parts.

vWhere separate throttles are employed in the secondary carburetors apart of the controlling mechanism is in the air manifold and a part ofsuch mechanism in the main carbureting unit, constituting a more or lesscomplicated structure, and presenting certain difficulties inmanufacture and Iin disas-- sembling for adjustment purposes.

It is, therefore, a further obj ectof this invention to simplify theconstruction to facilitate manufacture and adjustment thereof.

The present invention accomplishes these general objects by aconstruction which avoids the use of a separate throttle valve in eachof the separate secondary carburetors and which permits the use of thesimplest form of secondary carburetor associated with each engine intakeport. The present invention is embodied in a charge forming devicecomprising an air manifold which does not include any of the controlmechanism of the carburetor, and a main carburetor unit adapted to beattached to and supported by the air manifold, said structure includingchiefly a fuel bowl, the primary carburetors to which liquid fuel isdistributed from the fuel bowl, and yall of the valves and controlmechanism associated therewith for controlling the HOW of air throughthe air manifold and the How of primary fuel mixture from the primarycarburetors to the secondary carburetors at each engine intake port. Inthe disclosed form of this invention each secondary carf buretorcomprises a mixing chamber formed by an insert placed within each engineintake port before the air manifold is attached 100 one section beingattached to the main carburetor unit referred to and the other beingattached as an insert to each branch of the air manifold. In this waythe main carburetor unit maybe readilyattached to or detached from theair manifold, permitting the manufacture of the air manifold and themain carburetor as separate units.

In addition to securing these advanta es, this invention aims to providethe proper Fuel mixture for all conditions of speed and load of theengine, and particularly such mixtures as are economical and those whichwill aid in the rapid acceleration of the engine under differentconditions.

Further objects and advantages of the present invention will be apparentfro-m the following description, reference being had to the accompanyingdrawings, wherein a pre-- ferred form of embodiment of the presentinvention is clearly shown.

In the drawings:

Fig. 1 is a plan view of a charge forming device embodying the presentinvention;

Fig.v2 is a fragmentary sectional view on line 2-2 of Fig. 1;

Fig. 3 is an elevation thereof looking in the direction of the arrow 3of Fig. 1;

Figs. 4 and 5 are sectional views on lines 4-4 and 5-5 respectively ofFig. 3;

Fig. 6 is an end view of the carburetor unit looking in the direction ofthe arrow 6 of Fig. 3;

Fig. 7 is a view of the unit looking in the direction of the arrow 7 ofFig. 3;

Figs. 8 and 9 are sectional views on the lines 8-8 and 9 9,respectively, of Fig. 1;

Figs. 10, 11, 12 and 13 are fragmentary sectional views taken chiefly onthe lines 10-10, 11-11, 12 12, and 13-13, respectively, of Fig. 9;

Fig. 14 is a sectional view on line 14-14 of Fig. 7;

Fig. 15 is a sectional view on line 15-15 of Fig. 9;

Fig. 16 is a sectional view on line 16--16 of Fig. 6.

Fig. 17 is a detail view in vertical section of a modified form of thefuel valve shown in Fig. 10.

Fig. 18 is a plan view of such valve.

Fig. 19 is a vertical longitudinal section of amodified form of flowcontrol device.

Fig. 2O is a vertical section on line 20-20 of Fig. 19.

Referring to the drawings, 20 designates the air manifold having aninlet at 21 (see Fig. 9), having three branch pipes 22 eachcommunicating with a cylinder head intake port 23 of the conventionalsix cylinder engine, each intake port supplying fuel to a The carburetorunit comprises the conduit and primary carburetor block 30 and 31,respectively, which are secured together by screws 32 (see Figs. 6 and 7and which after being assembled are secured to the flange 25 by screws33. The members 30 and 31 in turn support a housing .34 attached theretoby screws 35 (see Figs. 1, 6 and 7). The housing 34 supports above it anair inlet member 36 which is attached by screws 36a, and the housing 34supports below it a frame 37 attached to it by screws 38. The frame 37sup ports the fuel bowl 39 attached thereto by screws 40. Between .thesevarious frame members sealing gaskets are placed as shown.

Fig. 2 shows' a section of the passage through which the liquid fuel isadmitted to the fuel bowl 39 and means for controlling the flow thereto.The frame member 37 is provided with a tubular extension 210 whichreceives the pipe connection 211 which isl tapped at 212 to receive apipe connected with the source of fuel supply. Fuel is required to passthrough a screen 213 Alocated in the passage 210 which is connected witha passage 214 leading to a valve seat member 215 providing a valve seat216 and outlet holes 217. The valve seat member 215 guides a floatoperated valve 218 which is yieldingly urged upwardly by lever 219carrying a float 220. The lever 219 is pivotally mounted upon a pin 221supported by brackets 222, one of which is shown in Fig. 2 attached tothe frame member 37.

The primary carburetors of the charge forming apparatus are locatedwithin the primary carburetor block 31. Each primary carburetor includesa horizontal passage 41 in the block 31 into which liquid fuel isdelivered through an orifice 42 provided by a bushing 43 screwed intothe block 31 the passage 41 constituting a primary mixing chamber. Theflow of fuel'from the orifice 42 into the primaryvmixing chamber 41 isinduced by the depression existing at the orifice 42 due to conditionswhich will be described later. Air for carrying the liquid issuing fromthe orifice 42 into the mixing chamber 41 is admitted through a hole 44in the housing 34 and through a bushing 45 having a bevelled lip 46extending close to the vertical center line of the orifice 42 for thepurpose of minimizing the effect upon the flow of v liquid fuel due tothe velocity of the air passing through the bushing 45. Each primarymixing chamber 41 receives its liquid fuel from a distributing blockwhich is attached to the primary carburetor block 31 by the screws 32 asshown in Figs. 6 and 7. yThe distributor block provides a liquid fuelmanifold 51 having separate -branches 52 each leading to one of themetering bushings 43. The entrance 53 to the manifold 51 is incornmun-ication with a passage 54 formed in a block 55 also secured tothe distributing block 50 by the screws 32. The passage 54 leads througha nipple 56 projecting downwardly from block 55 and conduit whichextends below the level 59 of fuel in the fuel bowl, said conduitcomprising connected pipes 57 land 58. v

o Under certain conditions fuel is admitted to the pipe 58 only througha metering plug 60 having an orifice 61. Fuel may be admitted to thepipe 58 also through a by-pass 62 having fuel inlet holes 63 which areshown covered by a valve 64 in Fig. 14.` Under certain conditions thevalve 64 will be lifted to permit. fuel to iiowthrough the 'hole 63 as72. Under engine operating conditions pro.

l ducing relatively high suction at the primary nozzles 43 and conse,uently' relatively high.

velocity of the flow o fuel through the pas-` sage 57, the meteringvalve will be lifted to permit the passage of a greater amount of fuelthrough-thepas'sage 73 around the valve 70 to the distributing canal 51.Normally this valve remains seated to keep the mixture lean below acertain medium speed, for example 30 miles per hour, when the vehicle isrunning-on the level.

lVhile the fuel is flowing upwardly through the passage 54, disc checkvalve member 74 is lifted from its seat 75, but when the fuel ceases tofiow the valve 74 will return to its seat so as to prevent emptying thedistributing manifold immediately. The upward movement of the valve 74is limited by its engagement with stop pins '76. The check valve 74prevents the dropping of the columnof liquid located above the level ofthe seat 75 in passage 54 down to the level of the fuel in bowl 39 whenthe engine speed is suddenly reduced with corresponding reduction invacuum above the check valve. Thus the valve 74 prevents starving theengine for a period, so that the engine will operate smoothly upon asudden reductlon in s eed. l

-pThe primary fuel' mixture passes from each primary carburetor to oneof the secondary carburetors to be described, through a separate fuelduct. Each one of these ducts includes a tube inserted in the airmanifold 2O so as to extend lengthwise of each one of its branches 22as4 shown in Figs. 5 and 9. In the case of the center branch 22 its pipe80 is connected directly with the outlet of the central primary mixingchamber 41 which is shown in Fig. 9. In the case of the end branches 22of the air manifold 20, each of their pipes 8O is connected with itsproper I mixing chamber 41 through a separate pipe 81. Each pipe 81 hasone end attached to the block 31 as shown in Fig. 1, andthe other endattached to a iange 82 secured to the air manifold 20 by screws 83. Itis apparent that -this construction will permit removal of the unitarycarburetor structure simply by removing the screws 33 .and'83.

The primary fuel mixture is caused to flow out of the pipes 80 and 81due to the difference in pressure at the outlet of such pipes and at theprimary mixing chambers 41. Each secondary carburetor is essentially aplain tube carburetor in-whi'ch the mixing chamber is provided by theengine cylinder head intake port 23 into which a primary mixture isdelivered and is lnixed with air received from an air manifold. As anaid to acceleration each engine vintake port 23 may receive a bushing 85providing a Venturi ,passage 86 for inducing more rapid flow of primarymixture from the pipe 80 whenit is desired to accelerate the enginerapidly. The 'venturi 86 assists in mixing the primary mixture with airin the secondary carburetors before passing into the engine cylinders.The venturi may, however, be omitted andother fiow accelerating meansemployed.

Owing to the fact that engine suction is effective on the secondarycarburetors successively there is some interchange of air between thesecondary carburetors, vwhen the suction is high in one and low inanother. Some fuel is always precipitated on the walls of the secondarymixing chambers and unless means were provided to prevent there might besome interchange of fuel as well as air be- `tween the said secondarycarburetors, which would cause difficulties in distribution. To preventsuch fuel interchange the branches 22 of the manifold are sloped towardthe engine ports, and the branches 2O slope downwardly toward the endsof the manifold. Any fuel deposited on the walls of any secondarycarburetor is prevented from flowing to( any other secondary carburetorby theaction of gravity.

Air for the primary and secondary carburetors is admitted through theport 90 in inlet member 36 controlled by a. spring loaded valve 91normally urged by 'a spring 92 against a seat 93'. From the member 36air may pass above a partition 94 in the frame 34 and thence through apassage 95 in the conduit or air throttle block 30 and into the entrance21 of the air manifold. Each primary mixing chamber 41 is connected withthe air passage 95 by a separate passage 96, the passages beingseparated by partitions 97 tending to prevent the primary carburetorsfrom interfering With one another. The passages 96 are of such size andso constructed and arranged as to maintain the same pressure in theprimary carburetors as is maintained in I fuel-air ratio at all speeds,as Well as to vary the sizeor shape of the mixing chambers 41 and theangle of the junction of the passages 96 With the chambers 41. Suchchanges may be required according to the effect of velocity, inertia orrestriction caused by changing the direction ofthe flow of primary airin conducting it from the air valve chamber 91a to the primarycarburetors.

The mixing chambers 41 are connected by an equalizer provided by ahorizontal passage 98 connected With vertical passages 99 for thepurpose of equalizing the suction at the nozzles 43. This constructionequalizes the pressure in the primary mixing chambers and tends tosecure more equal distribution of the liquid fue-l. Each passage 99provides a vent for minimizing eddy currents above the fuel nozzles,which, if present, Would upset uniformity of distribution of liquid tothe mixing chambers 41. A bafie 100 is provided in this conduit tominimize eddy currents in passages 96. These eddy currents would tend tointerfere With equal distribution of air to the mixing vchambers 41through the passages 96, and hence would upset the uniformity ofdistribution of the same fuel-air mixture to the various engine ports. i

The passage of air into the air manifold is controlled manually by abutterfly throttle valve 101 supported by a throttle rod 102. The flowof primary fuel mixture from the primary carburetors is controlled by asingle cylindrical valve member 103 having ports 104 each located inalignment With one of the mixing chamber passages 4l. The control of thevalves 101 and 103 will now be described:

Under conditions of relatively loW speed and load, the air throttle 101iskept closed and all of the fuel-mixture passes to the engine from theprimary mixing chambers 41 through the primary tube 8081. For example,up to a vehicle speed of about 15 to 20 miles per hour, When the enginepropels the vehicle on a level road, all of the fuel mixture may besupplied by the primary carburetors, the air valve 101 being closed. Dueto the fact that thesame depression is maintained in the air Chamber 91aand the primary mixing chambers 41, the relation of the movement of thevalves 103 and 101 is not one that must be maintained With a greatdegree of accuracy.

The speed at Which it is possible to operate the engine on fuel mixturesupplied entirely by the primary carburetors, that is, Without openingthe air throttle 101, depends llargely on the relative sizes of thetubes 80 and the air passages 96. In the carburetor hereindisclosedthese sizes are such that the engine may be runat speeds up to thatrepresented-by a vehicle speed of 20 to 25 miles per hour on a level,Without opening the valve 101.

It has been found that the best operation can be obtained at idle byentirely closing the valve 101 and taking all of the mixture from theprimary carburetors as indicated in Fig. 9. It is also possible however,to idle the engine and run at very low speeds With the air valve101-slightly open, or to provide it with a small hole to admitadditional air when idling.

Under all running conditions in which the air throttle 101 is open, asuper-rich mixture is carried through the primary tubes 80, 81 to thesecondary carburetors Where the mixture is diluted by the air passingthrough the air manifold so as to provide the desired mixture forrunning under these conditions. By super-rich mixture is meant one whichcontains a greater amount of fuel than is prop'- erly combustible ordesirable for steady running.

It may be here pointed out that the device herein disclosed differsmaterially from the earlier forms of the device in which separatethrottles Were employed at each secondary carburetor. In said earlierforms of device a super-rich7 mixture Was formed in the primarycarburetor at all times and under all operating conditions, because insuch devices there was always a flow of air through the main airmanifold under all operating conditions. To prevent the addition of suchair making too lean a mixture for proper combustion the primary mixturenecessarilyhad to be super-rich.

In the present device better vaporization of the fuel in theprimarycarburetors and better distribution of such fuel is secured thanin the earlier devices. Because of the passage of air through the mainair manifold and the termination of the outlet tubes from the primarycarburetors at points anterior ency of the fuel to condense and collecton the walls. n l

In the device disclosed herein the primary tubes terminate posterior tothe throttle where they are 4exposed to manifold suction under alloperating conditions. Theair velocity in such tubes is therefore high atall times securing superior vaporization and making the primary aircurrent a better medium for carrying the fuel. Also sincethe mixture issuper-rich only at higher motor speeds the diiiiculty of vaporizationof-such a mixture is not presented at all in the lower speed ranges, andsince the velocity in the primary tubes increases at high speeds, thediiliculty is largely negligible at any time.

The-metering of fuel and air by the carburetor is not effected bytheratio ,of air passing the air throttle 101 to the'air passing theprimary valve 103, when the passages 96 and the mixing chambers 41 areso designed vthat the depression at the fuel nozzles 43 is maintainedthe same as the depression in the air chamber 91a, and when theconstruction is such that dynamic suction or velocity head 7 does notaffect the suction at these nozzles.

However, it has been found dillicult, .in practice, owing to frictionalresistance, eddy currents and other factors to design a construction inwhich the effect of the dynamic suction or velocity head can beeliminated under all operating conditions and throughout all speedranges, particularly at higherv speeds. It is necessary therefore, thata definite relation be maintained between the opening movements of thevalves 101 and 103. the valve 101 starting to open at a definite pointin the opening movement of the valve 103, to prevent the mixturebecoming too rich due to the effect of velocity on the jets, whicheffect would be apparent at some definite speed.

For instance in the present construction the pressures in the passage 95and mixing chambers 41 remain substantially equal up to a vehicle speedof 20 to 25 miles an hour and the effectvof velocity head does notappear. At higher speeds, because of the factors above referred to,the'pressure in mixing chambers 41 becomes less than that in the passage95 and the consequent velocity head becomes effective to produceincreased mensurate with the increase in richness 0f the primarymixture. y

The coordination of the throttles 103and 101 will now be described. Theprimary throttle 103 is provided with spindles 105 rotatably mounted inthe wall of conduit 30v and to one of which is attached a lever 106which may be controlled in the usual manner by an accelerator pedal orby a throttle leverlocated at the top of the steering column. Thelever`106 carries a screw 107 for engaging a stop 108 to limit theclosing movement ofthe throttle. The lever 106 is provided with aplurality of tapped holes 109 each for receiving a screw 110 providing apivot for a link 111 having in its upper end a slot 112. The slot112'receives a screw 113 attached to a lever 114 which is clamped .tothe shaft 102 of the air throttle 101. It is therefore apparent that acertain amountof clockwise motion of the lever 106 ywill take place asviewed in Fig. 6 before the shaft 102 will be rotated in this direction;or, as viewed in Fig. 9 a certain amount of counter-clockwise rotationof the valve 103 towards open position will take place before the valve101 starts to open. TheV valve 101 is maintained closed by a spring 115coiled around the shaft 102 having one end bearing against the stud 116attached to the frame 30 and having'its other end received by one of aplurality of holes 117 provided by a cam 118 also attached to the shaft102. The spring is so biased that it tends to rotate the shaft 102 in acounter-clockwise direction as viewed in Fig. '6 rin order.to rotate thevalve 101 in a clockwise direction as viewed in Fig. 9 the 'twistingeffect of the spring can be varied by varying its connection with thecam 118.

, When -the engine is 'running idle, the air valve 91 will be' nearlyclosed.` Some of the air `for idling will be admitted to the primarymixing chambers 41 through the passage 44 and the bushings 45. As thethrottle 103 is opened to increase the speed of the y idle, or it couldbe provided with a small hole through. which a small amount of air couldbe supplied to the secondary carburetor during idling and under runningconditions such as referred to. As the engine speed increases from zerowith the opening of the throttle 103, the depression in the air chamber91a, will tend to increase,`therefore the valve 91 will move furtherfrom its seat to allow more air to be admitted to the primarylcarburetor in order to maintain the proper speed has ybeen reached, for.example, about 20-25 miles per hour at part load, the air throttle101will be opened to permit more air to pass through the secondarycarburetor in addition to that passing to it Ythrough the primarymixture tube 80. This prevents the engine mixture from becoming too richfor good performance and economy at higher speeds and under' part loadconditions as .heretofore fully set forth.

When running with wide open throttlev and the load is increasedwithout-change of I throttle position, as vwhen the vehicle on which thedevice is usedascends a hill, the depression in the air manifold andchamber 91m will decrease, permitting the spring 92 to move the valve 91toward closed position. This will tend to reduce the supply of airadmitted at the main air inlet and prevent a vdecrease indepression atthe fuel jets, preventing a tendency to lean the fuel mixture, whichwould otherwise occur under such conditions of operation.

In order to provide for the metering of more liquid fuel to the primarycarburetors under wide open throttle conditions to meet the condition ofhigh speed or full load, means are provided for lifting the valve 64shown in Fig. 14. This means includes a cam 120 (see Fig. V7) attachedto one of the throttle spindles-105 and adapted to engage a lever 121which is normally maintained by a spring 122 against a stop screw-123 attached to the block 31. The spring is connected with the lever 121byscrew 124 and with the block 31 by screw 125. The lever 121 is pivotedupon a screw 126 attachedto the block 31. The lever 121 is provided witha notched ear 127 which receives a rod 128 provided at its lower endwith the valve 64 (see Fig. 14). The upper end of the rod 128 is screwedinto a nut 129. The underside of the ear 127 bears against a washer 130;and a spring 131 is located between the Washer 130 and a collar `132 onthe rod 128. The rod 128 extends through a hole 133 in the frame member37. After the primary valve 103 has been opened a certain amount by theturning of the shaft 105 in a counterclockwise direction as viewed inFig. 7, the cam 120 will engage the lever 121 to cause it to moveclockwise and to lift the rod 128 and to cause the valve 64 to open theport 63. As the primary throttle 103 is ymoved towards closed position,the spring 122 will return the lever 121 against the stop 123 andthereby cause the lever to push against the spring 131 and move thevalve stem 128 downwardly to move the valve 64 into closed position.

When only the primary throttle 103 is open all of the liquid fuel ismetered through the orice 61 in order to keep the mixture lean forrelatively low speed and load operation nated. The valve 64 is notopened wide until the throttle is almost fully open. For example, thevehicle speed may be about 50 miles per hour when running on a levelroad before the valve 64 is entirely open.

The control of the air valve 91 for choking the carburetor will now bedescribed. The housing 34 has an integral, inwardly extending arm 140carrying a tubular extension 141 coaxial with the valve 91. A springretainer sleeve 142 having a grooved collar 143, is

vertically slidable upon the extension 141 and is lprovided with anannular groove 143 for receiving one end of the spring 92. The groovedcollar 143 receives the studs 144 of a yoked lever 145 (see Figs. 4 and9). Lever 145 is attached to a shaft 146 supported by the airport member36, and has an arm 14 exterior to the member 36 provided with a hole 148to which a carburetor choke rod 149 may be attached. Since the spring 92tends to move thesleeve 142 downwardly, the lever arm 147 will be movedin a counter-clockwise direction as viewed in Fig. 3, into engagementwith an adjustable stop screw 150 screwed into a hole in a clamp bracket151 which may be tightened yaround the screw 150 in adjusted position bytightening a screw 152. Therefore by adjusting the screw 150 thecompression of the spring 92 may be adjusted. To choke the carburetorwhen starting, the lever 147 is moved clockwise as viewed in Fig. 3, inorder to move the sleeve 142 upwardly and compress the spring 92 beyondits normal state of compression. Since the air valve 91 is held closed,a greater depression will occur above the metering orifice 42 in eachprimary carburetor and an extrarich priming mixture will be drawn intothe engine through the primary tubes 80. When the choke rod 149. isreleased the spring 92 will automatically return the lever 147 to itsposition against the stop screw- 150.

Under accelerating conditions when suddenly opening the throttles, thetransfer of fuel through the primary tubes 80, 81 to the engine tends tobe less rapid than the passage of air through the air manifold,consequently the mixture tends to run lean until the richer mixture hashad time to pass through the tubes 81, 80. This condition is aggravatedby the fact that the manifold the primary mixture tubes.

suction decreases rapidly onthe engine side of the throttle 101, whiletheair valve suction in chamber 91a 'and in the mixing passages 41increases'with the opening of the throttle 101, thereby causing adecrease in the pressure differential between the ends of To preventthis temporary leaning of the mixtures, the sudden opening of the airvalve 91 is retarded` by a dash pot to retard the flow of,air totheengines, and an additional amount of fuel is added to the air whichpasses through the air manifold.

The control of the air valve 91 by the dash pot will now be described.The valve 91 is attached to a rod 160 which passes through A the tubularpart 141 and through the tube 161 continuing from the lower end of thepart 141 .and attached to a partition plate 162 which is attached to theunderside of the partition 94 by screws 163. The lower end of the rod160 is at/tached to a piston rod 164 upon which a dash pot piston 165 ismounted for vertical sliding movement. A spring 166 which surrounds therod 164 is maintained under compression between `thel piston 165 and anut 167 attached to the rod 164. The spring urges the piston 165 againsta fia'nge 168 provided 'by the piston rod 164. The piston 165 isprovided with holes 169 communicating with an annular space 170 betweenthe flanges 168 and the bottom of the piston 165 when the latter restsupon said flange. The {iange 168 provides a seat for a relief valveprovided by the bottom of the piston 165. The flange 168 is providedwith holes 171 which may be closed by the check valve disc 172 which ismounted for vertical sliding movement on an extension 173 of the rod164, the separation of the valve 172 from its seat provided by theflange 1 68 being limited by a washer 174 attached ad]acent the bottomof the pistonrod 164.

The piston 165 cooperates with a dash pot cylinder 17 5 open at itsupper end and closed at its lower end by a plug 176. The cylinder 175 isguided for vertical movement by tubular guide 177 integralwith the framepart37. The guide 17 7 is provided with an opening 178 for permittingthe passage of liquid fuel into the cylinder 17 5 through an opening179. The opening 178 1s made longer vertically than the opening 179 sothat liquid fuel may enter the cylinder 1 75 in different positionsthereof. The cylinder 175 is provided with a U-shaped .pipe 180providing a` by-pass around the plston 165 in certain positions thereof(see Fig. 15). The inlet of the by-pass may be restricted if desired tocontrol the rate of flow therethrough. Such a restriction is illustrateddiagrammatically in Fig. 15. The pipe 180 is received by a vertical slot181 in the guide 177 and therefore prevents rotation of the'cylinder 175relative to the guide G 177. Therefore, the holes 17 8 and .179 arealways maintained in vertical alignment.

-The cylinder 175 is provided with means for moving it vertically undercertain conditions hereinafter more fully described,

such means comprising a groove 182 adja? cent its upper endwhichreceives studs 183 located on opposite sides of the cylinder 175and projecting from arms 184 attached .to a rod 185 supported by theframe member 37 and extending through the exterior thereof, where, asshown in.Fig. 6, the rod 185 is attached to a lever 186. Lever 186 isprovided withal series of holes 187 each for receiving a stud 188extending from a block 189. The stud provides a pivotal connection withthe lever 186 and block 189 and is threaded at its end toreceive a nut190 in order to maintain the parts 186 and 189 assembled. The block 189is provided with an oblong opening 191, which receives a spring 192 anda washer 193 both surround ing a rod 194 which is guided at 195 and 196by block 189. The washer 193 is pinned to the rod 194 so that the spring192 tends to urge the washer 193 against the wall 195 of the block1892and to maintain the relation between the parts 189 and 194 as shownin Fig. 6. The upper end of the rod 194 is bent inwardly to engage ahole in the end of a lever 197 which is pivoted upon a screw 198attached to the block 30. The lever 197 is located in the 'path `ofmovement of the cam 118 carried by the air throttle valve shaft 102. Aspring 199 is coiled around the screw 198 as shown in Fig. 8 and one endthereof bears against the block 30 and the other against the lever 197in a manner such as to urge the lever 197 in a clockwise direction asviewed in Fig. 3. Thespring therefore tends to urge the lever 186 in thesame direction and the cylinder 175 downwardly into its normal positionas shown in Fig. 9. On opening movement of valve 101 the lcam 118 actingthrough the medium oftending to cause the .valve 91 to open quickly. Thedownward movement of the piston 165 is retarded by the liquid in thebottom A of the cylinder 17 5 which cannot be moved relative to thepiston 165 since the holes 171 in the flange 168 which provide the checkvalve seat will be closed by the check valve disc 172. It is-to benoted, however, that the piston 165 is retarded by the liquid in thecylinder 17 5 only during a certain portion of the downward movement ofthe piston. Referring to Fig. 15 it will be noted that the piston 165 isnormally located with respect to the by-pass 180 so that after thepiston has moved about one-half of its permissible travel in thecylinder 175, the upper end of the by-pass 180 will be Completelyuncovered. Therefore, there is a relatively great resistance at thebeginning of the downward movement of the air valve 91 and thisresistance continues during only a small part of the downward .movementof the valve and then Agradually falls off as the by-pass 180 isuncovered. This device, therefore,- enables a sufficiently rich fuelmixture to be provided by the primary carburetor for the purpose ofaccelerating the engine fromlow speed up to any speed.

If it is desired to accelerate from a low speed.to a speed requiring atleast the partial .opening of the air throttle 101, means are providedfor adding more resi-stance to the opening of the' air valve 91 suchmeans being brought into operation by opening movement of said valve 101in order that a richer than normal fuel mixture may be provided afterthe air valve 101 starts to open, to provide fuel for acceleration frommoderate to higher speeds. This means includes the mechanism operated bythe cam 118 shown in Fig. 6. If the cam 118 is moved slowly in aclockwise direction corresponding to a slow opening of the valve 101,the dash-pot cylinder 175 will be lifted relatively slowly and verylittle modification of the effect on air valve 91 by the dash-pot willtake place. But if the valve 101 be opened rapidly, the camv118 willquickly force the lever 186 in a clockwise direction, and through theaction of the spring 192 will move the cylinder 175 upwardly, while thedash-pot 165 tends to move downwardly. This combined effect will tend toincrease the pressure of the liquid between the bottom of the cylinder175 and the piston 165, thereby tending to increase the retarding effectof the dash-pot on the opening movement of the valve 91.

This operation will tend to increase the depression at the primary fuelnozzles so that the primary mixture will be temporarily enriched.

The reason for employing a spring 192 for transmitting motion of lever197 to cylinder 175 to movethe latter upwardly is because of the inertiaof the mass of the parts which are connected with the lever 186. TooSudden downward movement of the lever 186 might cause undue strains onthese parts, therefore, motion is applied gradually through a spring.Moreover, the use of the spring permits a delayed lift in movement ofthe cylinder which permits the retarding effect on opening movement, ofthe air valve to take place through a greater period 'of time when thevalve 101 is opened. This insures the supply of a rich mixturethroughout the entire acceleration period.

In addition to the abovepmentioned devices to provide necessary fuel foracceleration an injector pump is provided which is effective primarilyat engine speeds above that at which valve 101 begins to open. When thevalve 101 begins to open, although the opening of the main air valve isretarded some air flows past the main air valve, and through the mainair passages, to the secondary carburetors. Although the'retarding ofthe air valve opening will produce a suiiiciently rich mixture in theprimary carburetors to take care of acceleration, it takes anappreciable time interval for such fuel mixture to pass to the engineports. The iniow of air past valve 101 takes place immediately andunless some means were provided to prevent, this secondary air would mixwith whatever primary mixture did reach the secondary mixing chamber andmomentarily weaken such mixture, so that the engine would not accelerateproperly. To prevent this weakening of the mixture an injector pump isprovided, such pump being operated by the air valve in its openingmovement to charge the secondary air referred to with fuel to form amixture in the secondary mixing chamber suiiciently rich foracceleration purposes. As shown in Figs. 9 andv 16, the cylinder 175 isprovided within the fuel bowl 39 with an outlet pipe 200 connected witha valve seat member 201 closed by ball valve 202 held in closedpositionby spring 203 which is caged within a fitting `204 attached tothe valve seat 201. A pipe.

205 attached to the fitting 204 extends to a l point above the air inletmember 36 and then downwardly at 206 into the air inlet 90 and so bentas to direct a jet of fuel against the edge of the valve 91. The suddenmovement of the throttle valves from any partially open to nearly fullopen position will cause suddenly a relatively great depression in theair chamber 91a and also a sudden lifting of the cylinder 175. Underthese conditions the pressure of the liquid between the bottom of thecylinder and the piston 165 will be sufficient to lift the valve 202from its seat and to cause a quantity of liquid to be squirted from thepipe outlet 206 on the valve 91. This liquid fuel is broken up as itflies downwardly from the edge of the valve, and mixes with the airpassingto both primary and secondary carburetors.

While the above described pump can be operated to pump fuel wherever theair valve is openedby a depression sufficient to open thevalve 202 andto overcome the effect of leakage past the piston, such depression isnot ordinarily communicated to the air valve on opening of the primarythrottle alone but only after the valve 101 begins to open.

liquid in the dash-pot may be great enough lao to overcome the spring166, whereupon the piston will be lifted from the flange 168 of thepiston rod to permit escape of liquid through the holes 169 in thebottom of the piston. As soon as the piston separates froml the flange168, it will remain separated until the pressure is relieved. Thisoperation is known as the functioning of the blow-off valve.

The cylinder 175 is provided with the bypass pipe 180 shown in Fig. 15for the urpose I'of producing a variable retarding e ected in accordancewith the position of the piston relative to the cylinder 175. As

previously explained, while the engine is idling, the air valve 91 isopened but slightly because the depression in the chamber 91a is low. Ifthe throttles are suddenly opened, the depression increases, and thevalve 91 tends to open quickly but its motion is retarded by thedash-pot since the check valve 172 closes the holes'171 in the flange168, requiring the liquid in the cylinder all to leak around the piston165. This damping effect persists relatively undiminished until theby-pass begins to be uncovered by the piston, during which interval, aricher mixture will be supplied tothe engine for purposes ofacceleration. Then the damping adually diminishes as the by-pass 180 isgele-ing uncovered to allow the valve 91 to open rapidly and supply airto' the 4engine to give the required power. The relation of the bypassto the piston and the restriction of the by-pass determines the durationof the valvedamping and this relation is varied automatically accordingto the position of the air throttle 101. The greater the initial openingof the air throttle 101 at the time it is suddenly opened further toaccelerate, the less will be the damping action. This variation ispresent because-less damping`of the air valve would be required whenmoving from a 25 to a 35'mile-per-hour throttle position than from a 15to a 35 mile-per-hour position, assuming that the gradeof the road issubstantially the same underboth conditions. The position of the by-pass180 relative to the piston 165 also determines the quantity of fuelpumped by the plston through tube 205.

As stated before, the sudden lifting of the dash-pot cylinder 175 has amomentary retarding effect upon the opening of the valve 91, because ittends to compress the liquid 1n the cylinder and to lift the pistonwith-- the lifting of the cylinder for a brief interval since the liquiddoes not have time to leak past the piston andpermit the piston to movedownwardly relative to thecylinder. Therefore even though the pistonwere at the point of opening the by-pass, this momentary retarding ofthe air valve 33 might take place when the air throttle 101 wasinitially partlyl opened. i

It is apparent from the foregoing description that the dash potconstitutesmeans for enriching the mixture only under part loadconditions and'on part throttle openings such as to produce low andintermediate vehicular speed. It is desired to accelerate to higherspeeds, requiring a substantial o'pening of the air throttle 101, therich mixture for acceleration is secured with the aid of the fuelinjector. The reason for not being able to obtain the accelerationmixture under all conditjons with the dash-pot alone is because whenaccelerating from a part throttle position of the air throttle 101 theby-pass 180 is practically uncovered by the piston 165; therefore thedash-pot would not retard suliiciently the further downward movement ofvthe air valve 91 for purposes of enriching the mixture. One reason forthe by-pass 180 can be explained by the following illustration. Supposethe vehicle is coasting at 40 miles per hour with the throttle closed,and the air valve 91 is nearly closed and then the throttles aresuddenly to a position which will cause the vehicle to attain a speed of50 miles per hour on the level. The air valve 91 must quickly move fromthe idle to the 40 mile-per-hour position. This position requiresconsiderable relative downward movement of the piston 165 in thecylinder 175,l and -the piston should not be retarded unduly, as theengine being already up to speed, requires no addition of accelerationfuel. Hence the by-pa 180- is required. There may be some retarding ofthe air valve 91 before the by-pass is uncovered. If the pressure in thedash-pot is too great under these conditions-the blow-off valve willrelievethe pressure so that the valve 91 may more quickly move to therequired position.

In Figs. 17 and 18 is disclosed av modified form of fuel valve which maybe substituted for valve 70. This valve comprises an outer member 220,normally resting on seat 71. The member 220 is provided with an orifice221, through which fuel Hows when member 220 is seated. Rate of flowthrough said orice is controlled by an inner valve member 222 movablymounted within member 220, movementthereof being controlled by a wire223, forming a guide and stop to limit upward movement of member 222.The wire extends through a slot in member 222 and is secured in thewalls of member 220. Member 222 is provided wth a fuel feeding orificeof smaller diameter than orifice 221. In operation at very low speedsboth members 220 and 222 are seated, and the orifice in member 222controlsthe iow. As the speed increases lll the member 222 is firstunseated permitting iow around said member, the iiow being c011- trolledat this time by orifice 221. On still higher speeds the member 220 islifted from its seat, permitting passage of fuel around as well asthrough such member.

In Figs. 19 and 20 is disclosed an alternative form of flow controllingmember which may be used in place of the Venturi tube 85. This membercomprises an outer sleeve 230, received in a recess formed in the end ofa manifold branch passage Where the latter is attached to the engineblock. At the opposite end of said-sleeve an inwardly proj ectlng lip231 is formed, said lip serving to collect any liquid deposited on theinner surface of such sleeve and direct same back .into the stream oflmixture flowing to the engine. Within the member a. plurality ofsubstantially straight cylindrical passagevvays are formed, throughwhich the mixture flows. These straight passages cause the mixture toflow in straight paths, eliminating eddy currents and turbulence, thuscausing some acceleration of flow. The passages may be formed by aplurality of separate cylinders secured Within the sleeve or by a singlesheet of metal bent in the form shown in VFig. 20. The primary tube 8Oterminates at a point adjacent the outer end of sleeve 231.

While the form of embodiment of the present invention constitutes apreferred form, it is to be understood that other forms might beadopted, all coming Within the scope of the claims which follow.

What is claimed is as follows:

1. A charge forming device for internal combustion engines havingl incombination a plurality of secondary mixing chambers, a plurality ofprimary carburetors for supplying primary mixture to said secondary.mixing chambers, a single throttle valve controlling flow of fuelmixture from the primary carburetors to the secondary mixing chambersand a single throttle controlling flow through the secondary mixingchambers.

2. A charge forming device for internal combustion engines having incombination a plurality of secondary mixing chambers, a plurality ofprimary carburetors for supplying primary mixture to said secondarymixing chambers, throttling means controlling flow of fuel mixture fromthe primary carburetors, throttling means controlling How through thesecondary carburetors and means for operating said throttling meansconcomitantly.

A charge forming device for internal combustion engines having incombination a plurality of secondary mixing chambers, a plurality ofprimary carburetors for supplying primary mixture to said secondarymixing chambers, throttling means controlling How of fuel mixture fromthe prima-ry carburetors, throttling means controlling flow through thesecondary carburetors and a common operating mechanism for 'saidthrottling means. I

4. A charge forming device for internal combustion engineshaving incombination a plurality of secondary mixing chambers, a plurality ofprimary carburetors for supplying primary mixture to said secondarymixing chambers, throttling means controlling flow of fuel mixture fromthe primary carburetors, throttling means controlling flow through thesecondary carburetors and a common operating mechanism for saidthrottling means said operating mechanism including means for operatingone of said throttling means in advance of the other.

5. A charge forming* device for internal combustion engines, having incombination a primary carburetor, a secondary carburetor, meansadmitting fuel and air to said primary carburetor to form a fuel mixtureof properly combustible proportions, means conveying said mixture to theengine ports undiluted With additional air at all 'engine speeds below acertain predetermined speed, a primary throttle for controlling the flowof said primary mixture and a secondary throttle operated by saidprimary throttle for regulating the iowA through the secondarycarburetor and controlling the admission of additional air thereto.

6. A charge forming device for internal combustion engines, having incombination a primary carburetor, a secondary carburetor, meansadmitting fuel and air to said primary carburetor to form a fuel mixtureof properly combustible proportions, means conveying said mixture to theengine ports undiluted with additionall air at all engine speeds below acertain predetermined speed,l a primary throttle controlling the flow ofsaid primary mixture, and a secondary throttle operated on openingmovement of said primary throttle when the latter is partly open, forregulating the flow through the secondary carburetor and the admissionof air thereto.

7. A charge forming device for internal combustion engines having incombination a primary carburetor, air and fuel inlets therefor, asecondary carburetor, a passage connecting the primary and secondarycarburetors, means for causing air to flow through said passage at highvelocity to carry fuel from the primary to the secondary carburetor andmeans for effecting a iow of air past the fuel inlet at' relatively lowvelocity to prevent the development of a velocity head at said fuelinlet.

8. A charge forming device for internal combustion engines having incombination a primary carburetor, air and fuel inlets therefor, asecondary carburetor, a passage connecting the primary and secondarycarburetors, means for causing air to flow through said passage at highvelocity to carry fuel from the primary to the secondary carburetor andmeans for effecting a flow of air past. the fuel inlet at relatively lowvelocity to prevent the development of `a velocity head at said fuelinlet, said last mentioned means comprising an air inlet in said passagebetneen the outlet end thereof and the fuel in et.

9. A charge forming device for an internal combustion engine having incombina-tion an intake passage therethrough, fuel and air inletstherefor, a valve controlling said air inlet, a dash-pot cylinderprovided with means for admitting fuel thereto and a movable pistonconnected to the air valve to control the movement thereof, means-formoving the dash-pot cylinder to control the movement of the air valve,and a fuel conduit extending from the dash-pot cylinder tothe carburetorintake passage, said dash-pot acting to pump fuel through such conduitto the intake passage.

10. A charge forming device for an inter-' nal combustion engine havinginv combination an intake passage therethrough, fuel and air inletstherefor, a throttle valve, a valve cont-rollingsaid air inlet, adash-pot cylinder provided with means for admitting fuel thereto and amovable piston connected to the air valve to control the movementthereof, means operated by the throttle for moving the dash-pot cylinderto additionally control the air valve and a conduit for conducting fuelfrom the dash pot to the carburetor in take passage on movement of thedash-pot piston or cylinder.

11. In a charge forming device for lnternal :combustion engines having aplurality 4of intake ports, an individual primary carburetor forsupplying a fuel mixture to each 'intake port, a .fuel supply chamber, acommon duct for feeding fuel from said fuel chamber to all of saidprimary carburetors and a suction operated fuel valve in said yfuel4feeding duct, said valve comprising two. separately-movable closureelements for dlfferentially controllingl the flow of fuel through thefuel feeding duct.

12.. In a charge forming device for an 1nternal combustion ,enginehaving a plurality of intake ports, a main air manifold .therefor havingbranches leading to said mtake ports, a primary carburetor associatedwith each branch of said manifold, conduits connected with said primarycarburetors and projecting into said branches of the main air manifoldfor conveying the primary m1xture thereto, and straightener elementspositioned in said branches adjacent the ends of said conduits forcausing the mixturepassing through said branches to flow in straightpaths.

13. A charge forming device for internal combustion engines havlngin'combmation, a plurality of secondarymixing chambers, a.

ing chambers, primary throttling means associated with said primarycarburetors, secondary -throttling 'means cooperating with saidsecondary mixing chambers and vcommon operating mechanism for saidprimary and secondary throttling means comprising a lost motionconnection;

14. A charge forming device for internal combustion engines having incombination,.a plurality of secondary mixing chambers, a. plurality oflprimary carburetors for supplying primary mixture to said secondarymixing chambers, a single primary throttle controlling all of saidprimary carburetors, a single secondary throttle controlling the flowthrough all of said secondary mixing chambers, and means for operatingthe two throttles simultaneously.

15. A charge forming device for internal combustion engines having incombination,

a plurality of secondary mixing chambers, a. plurality of primarycarburetors for supplying primary mixture to said secondary mix- Aingchambers, a single primary throttle controlling all of said primarycarburetors, a single secondary throttle controlling the flow throughall of said secondary mixing chambers, and common operating means forthe two throttles. y

16. A charge forming device for internal combustion engines having incombination, a plurality of secondary mixing chambers, a plurality ofprimary carburetors for supplying primary mixture to said secondarymixing chambers, a. single primary throttle controlling all of saidprimary carburetors, a single secondary throttle controlling the flowthrough all of said secondary mixing chambers, and common operatin meansfor the two throttles comprising a lost motion connection.

17. A charge forming device for internal combustion engines comprising aplurality of secondary mixing chambers, a plurality of primarycarburetors for supplying primary mixture tosaid secondary mixingchambers, means Nadmitting fuel and air thereto, a main airpassagesupplying air to said secondary mixing chambers, and means forequalizing the pressure in said primary carburetors comprising passagesconnecting said primary carburetors with each other and with the saidmain air passage.

1.8. A charge formingdevice for internal combustion engines comprisinga. plurality of buretors with the main air passage, and additionalpassages connecting the primary carburetors with the main air passageand adapted to leduce the velocity of flow through the primarycarburetors.

19. A charge forming device for internal combustion engines comprising aplurality of secondary mixing chambers, a plurality ofA primarycarburetors for supplying primary mixture to said secondary mixingchambers, means admitting fuel and air thereto, a main air passa esupplying air to said secondary mixing c ambers, pressure equalizingpassages connecting the main air passage With the primary carburetorsanterior to the fuel admitting means and additional passages connectingthe main air passage with the primary carburetors anterior to the saidequalizing passages to reduce the velocity of flow through the primarycarburetors.

20. A charge forming device for internal combustion engines comprisinga. secondary mixing chamber,a primary carburetor supplying a primarymixture of fuel and air to said secondary mixing chamber, primary andsecondary throttles controlling the primary carburetor and secondarymixing chamber respectively, a main air valve supplying air to theprimary carburetor and secondary mixing chamber, a dash pot controllingthe opening of the air valve and mechanism for simultaneously operatingboth the primary and secondary throttles and increasing the resistanceof the dash pot to opening movementv of the air valve.

21. A charge forming device for internal combustion engines comprising asecondary mixing chamber, a primary carburetor supplying a primarymixture of fuel and air to sald secondary mixing chamber, primary andsecondary throttles controlling the primary carburetor and secondarymixing chamber respectively, a suction operated air valve adapted toopen as said throttles are opened, means for resisting the openingmovement of saidvalve and means for simultaneously operating both saidthrottles and increasing the resistance of said resisting means to theopening movement of said air valve.

22. In a charge forming device for internal combustion engines having aplurality of intake ports, an individual primary carburetor forsupplying a fuel mixture to each intake port, a fuel supply chamber, acommon duct for feeding fuel from said fuel chamber to all of saidprimary carburetors and a compound valve in said fuel feeding duct, saidvalve comprising two independently operable and telescopically arrangedclosure elements for differentially controlling the flow of fuel.

23. In a charge forming device for internal combustion engines having aplurality of intake ports, an individual primary carburetor forsupplying a fuel mixture to each intake port, a fuel supply chamber, acommon duct for feeding fuel from said fuel chamber to all of saidprimary carburetors and a compound valve in said fuel feeding ductcomprising two independently operable closure elements having passagesformed therein to permit flow of fuel When said closure elements areseated.

24. In a charge forming device for internal combustion engines having aplurality of intake ports, an individual primary carburetor forsupplying a fuel mixture to each intake port, a fuel supply chamber, acommon duct for feeding fuel from said fuel chamber to all of saidprimary carburetors and a compound valve in said fuel feeding ductcomprising two independently operable closure elements having passagesof different sizes formed therein, said closure elements being adaptedto control the fuel How successively.

25. In a charge forming device for internal combustion engines having aplurality of intake ports, an individual primary carburetor forsupplying a fuel mixture to each intake port, a fuel supply chamber, acommon duct for feeding fuel from said fuel chamber to all of saidprimary carburetors, and a suction operated valve in said fuel feedingduct comprising two separately operable closure elements having passagestherethrough and adapted to differentially control the ovv of fuelthrough said duct.

26. In a charge forming device for internal combustion engines having aplurality of intake ports, an individual primary carburetor forsupplying a fuel mixture to each intake port, a fuel supply chamber, acommon duct for feeding fuel from said fuel chamber to all of saidprimary carburetors,` and a suction operated valve in said fuel feedingduct comprising tivo separately operable closure elements havingpassages of different sizes formed therein and adapted to be unseatedsuccessively as the suction increases, whereby the How of fuel isprogressively increased.

27. In a charge forming device for internal combustion engines having aplurality of intake ports, an individual primary carburetor forsupplying a fuel mixture to each intake port, a fuel supply chamber, acommon duct for feeding` fuel from said fuel chamber to all of saidprimary carburetors, and a suction operated valve in said fuel feedingduct. comprising two separately operable closure elements of differentWeights, the lighter of said elements having a relatively small fuelpassage therein and the heavier of said elements having a largerpassage` therein, whereby the size of the fuel passage is proagressively increased as the suction increases.,

28. A charge forming dcvice for internal combustion engines having incombination, an intake passage, fuel and air ports therefor, anautomatic air valve controlling the air port, a throttle, means forenriching the mixture at low and high speeds comprising a dash pot 'forresisting the opening movement of the air valve having a movablepistonland movable cylinder, and an additional means for enriching themixture at relatively high speeds.

29. A charge forming device for internal combustion engines having incombination, an intake passage, fuel and air ports therefor, anautomatic air valve controlling the air port, a throttle, means forenriching the mixture at low and high speeds comprising a dash pot forresisting the opening movement of the air valve having a movable pis- Iton and movable cylinder, an additional,

means for enriching the mixture at high speeds, and a fuel deliveryconduit extending from the dash pot to the intake passage.

30. A charge forming device for internal combustion engines having incombination an intake passage, fuel and air ports therefor, an automaticair valve controlling the air port, a throttle, means for enriching themixture at low and high speeds comprising a dash pot for resisting theopening movement of the air valve having `a piston secured to the airvalve stem and a movable` cylinder adapted to be moved by said throttle,and an additional means operable by the throttle for enriching themixture at relatively high speeds.

31. A charge forming device for internal combustion engines comprising amixing chamber, fuel and air inlets therefor, a fuel reservoir, a fuelduct connecting said reservoir with the fuel inlet, and a compound valvein said fuel duct comprising two independently operable closure elementshaving passages formed therein to permit flow of fuel when said closureelements are seated.

32. A charge forming device for internal combustion engines comprising amixing chamber, fuel and air inlets therefor, a fuel reservoir, a fuelduct connecting said reservoir with the fuel inlet, and a suctionoperated valve in said fuel duct comprising two separately operableclosure elements having passages therethrough and adapted todifferentially control the fiow of fuel through said duct.'

33. A charge forming device for internal combustion engines comprising amixing chamber, fuel and air inlets therefor, a fuel reservoir, a fuelduct connecting said reservoir with the fuel inlet, and asuctionvoperated valve in said fuel duct comprising separately operableclosure elements having passages of different sizes formed therein andadapted to be unseated successively as the suction increases, wherebythe iiowv of fuel is rogressively increased. p l n testimony whereof Ihereto aix my signature.` l

W'ILFORD H. TEETER.

